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Advances in Weight Loss Management and Medical Devices
Milovancev, et al., Adv Weigh Loss Manag Med Dev 2016, 1:1
http://dx.doi.org/10.4172/AWMD.1000102
Research Article
Open Access
Body Weight Reduction and QTc Interval in Obesity
Aleksandra Milovancev1, Edita Stokic2, Djordje S. Popovic2,*, Dragana Tomic-Naglic2, Olivera Rankov3 and Branislava Ilincic4
Institute for Pulmonary Diseases of Vojvodina, Sremska Kamenica, Medical Faculty, University of Novi Sad, Serbia
Clinic for Endocrinology, Diabetes and Metabolic Disorders, Clinical Center of Vojvodina, Medical Faculty, University of Novi Sad, Serbia
3
Clinic for Gynecology and Obstetrics, Clinical Center of Vojvodina, Medical Faculty, University of Novi Sad, Serbia
4
Institute for Laboratory Medicine, Clinical Center of Vojvodina, Medical Faculty, University of Novi Sad, Serbia
1
2
Abstract
Introduction: Obesity is associated with wide variety of electrocardiographic (ECG) abnormalities. Prolonged
QTc interval is common in obesity and it represents a delayed ventricular repolarisation which is associated with
ventricular arrhythmias, syncope and sudden cardiac death. The aim of our study is to evaluate the effects of weight
reduction on QTc interval in obese subjects.
Materials and Methods: The study included 74 obese subjects aged 41.78 ± 10.70 years, treated with a lowcalorie diet (800 kcal/day) for two weeks. All patients underwent a standard resting 12-lead surface ECG before and
after the treatment. QTc intervals were corrected by Bazett’s formula.
Results: The average loss in body weight was 10.26 ± 3.63%, and the average reduction in body mass index
was 9.39 ± 4.23%. There were statistically significant differences for all electrocardiographic parameters (p<0.01)
except for the QTc dispersion (p>0.05) before and after the treatment with low-calorie diet. Heart rate was also
statistically significant reduced after the low-calorie diet treatment. Prevalence of prolonged QTc interval was 24.32%
before and 9.21% after the treatment.
Conclusion: The results show that obesity causes prolongation of QTc interval. Significant weight reduction of
about 10% leads to favorable electrocardiographic changes and significant shortening of the QTc interval.
Keywords: Obesity; Electrocardiography; Arrhythmia; Weight loss;
Sudden cardiac death
Introduction
Obesity is defined as an excessive accumulation of body fat to the
extent that causes serious health problems and complications in many
different organs and organ systems [1]. Obesity follows an increased
risk of developing chronic diseases such as cardiovascular diseases, hypertension, coronary heart disease, cerebrovascular disease and peripheral arterial disease [2]. Obesity is associated with a higher incidence of
ventricular arrhythmias that can cause sudden cardiac death [3] even
in those patients who had no previously known heart disease [4,5].
Cardiovascular complications in obesity are associated with various
electrocardiographic (ECG) abnormalities. One of them is prolonged
QTc interval, which hallmarks delayed ventricular repolarization, and
it represents a risk factor for the development of ventricular tachyarrhythmias, syncope and sudden cardiac death [6,7]. Prolonged QTc
interval in obesity was first described twenty years ago [8]. Many studies that followed showed that obesity can cause prolonged QTc interval
[9-11]. Much of comorbidities associated with obesity can be improved
or prevented with body weight (BW) reduction [12]. Effects of changes
in body mass index (BMI) on cardiovascular risk are verified in the
Framingham study. It was noticed that 20% of BW loss reduces the risk
of cardiovascular diseases by 40% [13]. Many studies observed the effects of weight reduction on the QTc interval in obese patients, but the
results are conflicting. The most of the studies observed that QTc interval is shortening during the weight reduction [14-17], but some studies
haven’t shown significant changes in the QTc interval during weight
reduction [12,18]. It is surely important to monitor the QTc interval
during the treatment of obesity in order to prevent adverse cardiovascular events. The aim of our study is to evaluate the effects of weight
reduction on QTc interval in obese patients.
Adv Weigh Loss Manag Med Dev
ISSN: AWMD, an open access journal
Materials and Methods
Obese men and women were recruited from the Clinic for
Endocrinology, Diabetes and Metabolic Disorders, Clinical Center of
Vojvodina, Novi Sad. Subjects were included in weight loss program.
Inclusion criteria were age 18 to 65 and BMI ≥ 30 kg/m². We excluded
those with a previous history of diabetes mellitus, hypertension, heart,
hepatic, kidney, psychiatric, malignant, infectious disorders and those
taking drugs that can influence QT interval. Levels of potassium, sodium
and calcium were measured before and during the investigation and we
have excluded 3 patients because of existence of electrolyte imbalances.
The study was performed according to the Declaration of Helsinki, and
informed consent was obtained from all participants. The study has
local ethics committee approval.
With the subjects wearing light indoor clothes and no shoes BW and
body height (BH) were measured using calibrated beam-type balance
to the nearest 0.1 kg and Harpenden anthropometer to the nearest 0.1
cm respectively, and BMI was calculated (BMI=BW/BH2 (kg/m2)).
The obese subjects were treated with conventional diet consisting
*Corresponding author: Djordje S. Popovic, Clinical Center of Vojvodina, Hajduk
Veljkova 1, 21000 Novi Sad, Serbia, Tel: +38163551606; +381214843758; E-mail:
[email protected]
Received December 03, 2015; Accepted January 06, 2016; Published January
12, 2016
Citation: Milovancev A, Stokic E, Popovic DS, Naglic DT, Rankov O, et al. (2016)
Body Weight Reduction and QTc Interval in Obesity. Adv Weigh Loss Manag Med
Dev 1:102. doi:10.4172/AWMD.1000102
Copyright: © 2016 Milovancev A, et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited.
Volume 1 • Issue 1 • 1000102
Citation: Milovancev A, Stokic E, Popovic DS, Naglic DT, Rankov O, et al. (2016) Body Weight Reduction and QTc Interval in Obesity. Adv Weigh Loss Manag Med Dev
1:102. doi:10.4172/AWMD.1000102
Page 2 of 8
of a low-calorie diet (LCD) of 800 kcal/day. During the active weight
loss programme which lasted two weeks all subjects were required to
eat the same low calorie diet of nutritionally balanced prepared foods.
The prescribed diet contained approximately 30% of calories from fats,
50% from carbohydrates and 20% from proteins. The subjects were
required to take three to four liters of sparkling mineral water per day,
and a multivitamin tablets (Oligovit), which contains: Vitamin A 5000
IU; Vitamin B1 5 mg; Vitamin B2 5 mg; Vitamin B6 2.5 mg; Vitamin
B12 2.5 mg; 50 mg of nicotine amide; vitamin C 100 mg; vitamin D3
500 IU; Vitamin E 12.5 mg; Calcium pantothenate 10 mg; CaHPO4 200
mg; fluoride 0.5 mg; iron 10 mg; copper 0.5 mg; manganese 0.5 mg;
cobalt 0.05 mg; magnesium 3 mg; zinc 0.75 mg; molybdenum 0.1 mg;
potassium 2.5 mg; methyl hydroxybenzoate 0.06 mg; the energy value
of this product was 6.68 kJ (1.59 kcal).
ECG records were done twice at approximately the same time
each morning in fasting subjects on day 0 (at the beginning of weight
loss program) and day fourteen, at the end of intervention. All of the
subjects in the study group underwent a standard resting 12-lead
surface ECG recorded at a paper speed of 25 mm/s and gain of 10
mm/mV. The ECGs were analyzed by one reader who was unaware
of the characteristics of the subject. Reader was trained to obtain the
minimum of intravariability of measurements. The ECG parameters
were measured manually by using graduated lens. QT intervals were
measured from the beginning of the QRS complex to the visual return
of the T-wave to the isoelectric line. QT intervals and R-R intervals
were measured in all of 12 derivations in three consecutive cardiac
cycles and then averaged. The longest QT was accepted as the QTmax
interval, and the shortest QT was accepted as the QTmin interval.
The difference between the QTcmax and QTcmin was defined as QTc
dispersion. All the intervals were corrected by the Bazett formula=QT
Interval/√ (RR interval). Statistical analyses were performed using the
SPSS (version 11.0) software. All variables were expressed as mean ±
standard deviation or percentage (%). We used the Mann‑Whitney
test for nonparametric unpaired variables when comparing the groups
before and after weight reduction and the Student’s t test for parametric
variables, p value of 0.05 or less was considered to indicate statistical
significance.
Results
The study included 74 obese subjects, 41.78 ± 10.70 years old
treated with LCD. The average loss in BW was 10.26 ± 3.63%, and the
average reduction in BMI was 9.39 ± 4.23%. The characteristics of the
study population are listed in Table 1. There were statistically significant
differences in BW and BMI before and after the treatment (p<0.01).
Prevalence of prolonged QTc interval (over 440 msec) was 24.32% in
obese subjects before treatment. After weight reduction prevalence of
prolonged QTc interval was reduced to 9.21%. There were statistically
significant differences for all electrocardiographic parameters (p<0.01)
except for the QTc dispersion (p>0.05) before and after the treatment
with low-calorie diet. Decline in heart rate (HR) after the treatment was
also statistically significant (Table 1). There was statistically significant
difference in systolic blood pressure before and after weight reduction
program (131.00 ± 21.92 mmHg vs. 113.33 ± 8.84 mmHg, p<0.01)
while the change in diastolic blood pressure was not significant (84.90
± 13.26 mmHg vs. 78.50 ± 4.76 mmHg, p>0.05). Changes in blood
pressure were not related to QTc interval changes. Considering the
lipid profile, there was significant decrease in triglyceride levels (1.69 ±
1.49 mmol/l vs. 1.02 ± 0.58 mmol/l, p<0.01), while the changes in total
cholesterol (5.34 ± 1.20 mmol/l vs. 5.04 ± 0.92 mmol/l, p>0.05), LDL
cholesterol (3.56 ± 1.01 mmol/l vs. 3.14 ± 0.80 mmol/l, p>0.05) and
Adv Weigh Loss Manag Med Dev
ISSN: AWMD, an open access journal
Before
After
x̄ ± SD
x̄ ± SD
BW (kg)
140.78 ± 31.74
BMI (kg/m2)
Parameter
t-value
p-value
125.45 ± 26.53
3.19
p<0.01
49.52 ± 9.67
44.36 ± 8.16
3.51
p<0.01
QTc (msec)
422.82 ± 24.21
401.88 ± 27.32
4.93
p<0.01
QTcmax (msec)
446.07 ± 30.26
426.86 ± 31.03
4.91
p<0.01
QTcmin (msec)
396.89 ± 25.90
379.27± 31.05
4.79
p<0.01
QTc disp (msec)
49.18 ± 21.80
47.58±16.90
0.53
p>0.05
HR (bpm)
70.61 ± 10.47
65.15 ± 10.10
4.08
p<0.01
BW: Body Weight, BMI: Body Mass Index, QTcmax: QTc Maximum, QTcmin: QTc
minimum, QTc disp: QTc Dispersion, HR: Hearth Rate, bpm: Beats per Minute
Table 1: Characteristics of subjects before and after weight reduction treatment.
HDL cholesterol (1.06 ± 0.23 mmol/l vs. 1.14 ± 0.31 mmol/l, p>0.05)
levels before and after weight reduction were not significant. Also, there
were no significant correlations between changes in lipid parameters
and QTc interval changes.
Discussion
In our study, obese subjects, after the treatment with LCD, showed
a significant reduction in BW and BMI. Obesity is associated with a
numerous of electrocardiographic abnormalities. Some of them are
harmless but some may represent changes in cardiac morphology
which are associated with obesity or its comorbidities [19]. Ventricular
repolarization disturbances caused by left ventricle enlargement and
eccentric hypertrophy of the left and right ventricular wall in obesity
may lead to malignant cardiac arrhythmias and sudden cardiac
death. Many of these changes are reversible [20,21]. Alpert et al. and
Alexander et al. showed that significant weight loss in extremely obese
patients leads to favorable cardiac structural, hemodynamic and
electrocardiographic changes [22-24]. Al-Salameh et al. concluded that
weight reduction after sleeve gastrectomy in morbidly obese patients
was associated with a significantly lower QTc interval [25].
In our research 24.3% obese patients had prolonged QTc interval
before the treatment and after weight reduction percentage of
prolonged QTc interval was significantly reduced to 9.21%. BW loss
of 10.26 ± 3.63% is associated with significant shortening of QTc,
QTcmax, QTcmin intervals and HR reduction. QT dispersion was
not significantly shortened. Shortening of the QTc interval and HR
reduction decreases the risk of potentially fatal arrhythmias that lead to
a reduction in cardiovascular mortality [12]. In clinical studies dealing
with this problem, the conclusions are still controversial. Mshui et al.
showed that QTcmax and QTcmin intervals decreased after weight
reduction, with no significant change in QTc dispersion [26]. Similar
results we have obtained in our study. In contrast, Grupta et al. reveled
that decrease in QT dispersion was due to increase in the QTcmin
interval in most patients treated with liquid protein diet for weight
loss [27]. In our research, we concluded that a significant loss in BW
of about 10% leads to favorable electrocardiographic changes and the
significant shortening of the QTc interval.
Electrolyte imbalances that occur during obesity treatment may
aggravate or prolong QTc. The risk of sudden cardiac death in the
obese patients is influenced by structural, functional and metabolic
Volume 1 • Issue 1 • 1000102
Citation: Milovancev A, Stokic E, Popovic DS, Naglic DT, Rankov O, et al. (2016) Body Weight Reduction and QTc Interval in Obesity. Adv Weigh Loss Manag Med Dev
1:102. doi:10.4172/AWMD.1000102
Page 3 of 8
factors [28]. Therefore, it is necessary to monitoring these patients
electrocardiographically to prevent potentially fatal arrhythmias and
sudden cardiac death.
Acknowledgements
We would like to thank to all our colleagues who helped us during the work on
this study, and to the participants without whom this study could not be performed.
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Citation: Milovancev A, Stokic E, Popovic DS, Naglic DT, Rankov O, et al.
(2016) Body Weight Reduction and QTc Interval in Obesity. Adv Weigh Loss
Manag Med Dev 1:102. doi:10.4172/AWMD.1000102
Adv Weigh Loss Manag Med Dev
ISSN: AWMD, an open access journal
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